In connection with known plastic injection molding tools for producing hollow or domed workpieces, the rear tool half, customarily called a core, which shapes the inner wall of the workpiece, is customarily fastened on a bridge-like so-called support structure, which in turn is supported on a base or sole plate which is to be connected to a fixing plate of the injection molding machine. The bridge-like support structure is required for providing a space for the movement of an ejector plate located underneath it, which can be moved forward and back over a defined stroke by means of a linear drive mechanism supported on the bridge-like support structure, and is connected with the ejectors and oblique slides by means of push rods. Because the push rods moving the oblique slides are arranged inclined in respect to the feeding direction and are conducted, longitudinally displaceable, through bores correspondingly extending obliquely through the bridge-like support structure, they displace the oblique slides sideways during the forward movement of the ejector plate, so that they can be retracted out of protrusions or undercuts of the lateral wall of the workpiece, so that in the end the latter can be lifted off the core of the mold and ejected. The oblique position of the push rods of the oblique slides requires a relatively large ejector plate and therefore also a comparatively large hollow chamber which must be bridged. Such a conventional injection molding tool is described in U.S. Pat. No. 5,922,368, wherein the center front area of the core overlaps the oblique slides and is used as an ejector.
The known construction of the plastic injection molding tools with an ejector plate, which can be moved underneath a bridge-like support structure and has push rods, has the disadvantage that the manufacture of the tool from a multitude of movable parts is complicated and very expensive, wherein furthermore there is the danger of sagging of the bridge-like support structure and deformation of the relatively long push rods.